diff --git a/tools/update-cares.sh b/tools/update-cares.sh
index b43f850bebaa95..0f1aa2c9804903 100755
--- a/tools/update-cares.sh
+++ b/tools/update-cares.sh
@@ -24,28 +24,28 @@ cleanup () {
 
 trap cleanup INT TERM EXIT
 
-ARES_REF=cares-$(echo $ARES_VERSION | tr . _)
-ARES_TARBALL=c-ares-$ARES_VERSION.tar.gz
+ARES_REF="cares-$(echo $ARES_VERSION | tr . _)"
+ARES_TARBALL="c-ares-$ARES_VERSION.tar.gz"
 
 cd "$WORKSPACE"
 
 echo "Fetching c-ares source archive"
-curl -sL -o $ARES_TARBALL https://github.com/c-ares/c-ares/releases/download/$ARES_REF/$ARES_TARBALL
-gzip -dc $ARES_TARBALL | tar xf -
-rm $ARES_TARBALL
+curl -sL -o "$ARES_TARBALL" "https://github.com/c-ares/c-ares/releases/download/$ARES_REF/$ARES_TARBALL"
+gzip -dc "$ARES_TARBALL" | tar xf -
+rm "$ARES_TARBALL"
 mv "c-ares-$ARES_VERSION" cares
 
 echo "Removing tests"
-rm -rf $WORKSPACE/cares/test
+rm -rf "$WORKSPACE/cares/test"
 
 echo "Copying existing .gitignore, config and gyp files"
-cp -R $DEPS_DIR/cares/config $WORKSPACE/cares
-cp $DEPS_DIR/cares/.gitignore $WORKSPACE/cares
-cp $DEPS_DIR/cares/cares.gyp $WORKSPACE/cares
+cp -R "$DEPS_DIR/cares/config" "$WORKSPACE/cares"
+cp "$DEPS_DIR/cares/.gitignore" "$WORKSPACE/cares"
+cp "$DEPS_DIR/cares/cares.gyp" "$WORKSPACE/cares"
 
 echo "Replacing existing c-ares"
-rm -rf $DEPS_DIR/cares
-mv $WORKSPACE/cares $DEPS_DIR/
+rm -rf "$DEPS_DIR/cares"
+mv "$WORKSPACE/cares" "$DEPS_DIR/"
 
 echo "All done!"
 echo ""